Faribourz Payvandi

The anti-cancer drug lenalidomide inhibits angiogenesis and metastasis via multiple inhibitory effects on endothelial cell function in normoxic and hypoxic conditions

Lenalidomide (Revlimid) is approved for the treatment of transfusion-dependent patients with anemia due to low- or intermediate-1-risk Myelodysplastic Syndromes (MDS) associated with a del 5q cytogenetic abnormality with or without additional cytogenetic abnormalities, and in combination with dexamethasone for the treatment of multiple myeloma patients who have received at least one prior therapy. Previous reports suggest that lenalidomide is anti-angiogenic and this property appears to be related to efficacy in patients with MDS. We have investigated the effect of lenalidomide on the formation of microvessels in a novel in vitro angiogenesis assay utilizing human umbilical arterial rings and in a capillary-like cord formation assay using cultured primary endothelial cells. We found that lenalidomide consistently inhibits both sprout formation by arterial rings and cord formation by endothelial cells in a dose-dependent manner. We also found an inhibitory effect of lenalidomide on the associations between cadherin 5, beta-catenin and CD31, adherens junction proteins whose interaction is critical for endothelial cell cord formation. Furthermore, lenalidomide inhibited VEGF-induced PI3K-Akt pathway signaling, which is known to regulate adherens junction formation. We also found a strong inhibitory effect of lenalidomide on hypoxia-induced endothelial cell formation of cords and HIF-1 alpha expression, the main mediator of hypoxia-mediated effects and a key driver of angiogenesis and metastasis. Anti-metastatic activity of lenalidomide in vivo was confirmed in the B16-F10 mouse melanoma model by a >40% reduction in melanoma lung colony counts versus untreated mice. Our results suggest that inhibitory effects on microvessel formation, in particular adherens junction formation and inhibition of hypoxia-induced processes support a potential anti-angiogenic and anti-metastatic mechanism for this clinically active drug.

The Synthetic Compound CC-5079 Is a Potent Inhibitor of Tubulin Polymerization and Tumor Necrosis Factor-α Production with Antitumor Activity

We have found that the synthetic compound CC-5079 potently inhibits cancer cell growth in vitro and in vivo by a novel combination of molecular mechanisms. CC-5079 inhibits proliferation of cancer cell lines from various organs and tissues at nanomolar concentrations. Its IC(50) value ranges from 4.1 to 50 nmol/L. The effect of CC-5079 on cell growth is associated with cell cycle arrest in G(2)-M phase, increased phosphorylation of G(2)-M checkpoint proteins, and apoptosis. CC-5079 prevents polymerization of purified tubulin in a concentration-dependent manner in vitro and depolymerizes microtubules in cultured cancer cells. In competitive binding assays, CC-5079 competes with [(3)H]colchicine for binding to tubulin; however, it does not compete with [(3)H]paclitaxel (Taxol) or [(3)H]vinblastine. Our data indicate that CC-5079 inhibits cancer cell growth with a mechanism of action similar to that of other tubulin inhibitors. However, CC-5079 remains active against multidrug-resistant cancer cells unlike other tubulin-interacting drugs, such as Taxol and colchicine. Interestingly, CC-5079 also inhibits tumor necrosis factor-alpha (TNF-alpha) secretion from lipopolysaccharide-stimulated human peripheral blood mononuclear cells (IC(50), 270 nmol/L). This inhibitory effect on TNF-alpha production is related to its inhibition of phosphodiesterase type 4 enzymatic activity. Moreover, in a mouse xenograft model using HCT-116 human colorectal tumor cells, CC-5079 significantly inhibits tumor growth in vivo. In conclusion, our data indicate that CC-5079 represents a new chemotype with novel mechanisms of action and that it has the potential to be developed for neoplastic and inflammatory disease therapy.

A novel technique for quantifying changes in vascular density, endothelial cell proliferation and protein expression in response to modulators of angiogenesis using the chick chorioallantoic membrane (CAM) assay

Reliable quantitative evaluation of molecular pathways is critical for both drug discovery and treatment monitoring. We have modified the CAM assay to quantitatively measure vascular density, endothelial proliferation, and changes in protein expression in response to anti-angiogenic and pro-angiogenic agents. This improved CAM assay can correlate changes in vascular density with changes seen on a molecular level. We expect that these described modifications will result in a single in vivo assay system, which will improve the ability to investigate molecular mechanisms underlying the angiogenic response.